1. Field of the Invention
The present invention relates to a safety system and method for use with hyperbaric chambers. More specifically, the invention is an overpressure protection system and method for interposition between a hyperbaric chamber and a corresponding oxygen supply that both vents the chamber and shuts off oxygen flow upon the occurrence of a predetermined pressure condition. An improved hyperbaric chamber incorporating an overpressure protection system is also provided.
2. Description of the Related Art
Hyperbaric chambers are used in diving to help alleviate symptoms of decompression sickness as well as in the treatment of wounds and disease. During use, the patient sits or lays inside the hyperbaric chamber, typically on a mattress in the supine position, whereafter the hyperbaric chamber is sealed and pressurized to approximately thirty pounds per square inch (psi) using pure oxygen. Increasing pure oxygen pressure within the chamber to this level assists the body in recovering from wounds by increasing the amount of oxygen available to the cells and bloodstream.
When dealing with a pure oxygen environment, there are several significant risks. For example, pure oxygen supports combustion, and any spark or unintentional open flame could lead to an explosion. Also, if the recommended pressure is exceeded within the hyperbaric chamber, the chamber might structurally fail, which can cause the chamber to blow apart at high speed with an additional risk of injury to those in the room or the patient in the chamber.
To address these problems, hyperbaric chambers are typically fixed with overpressure relief valves set for a predetermined pressure, which is typically approximately thirty-five psi. In other words, should the pressure within the hyperbaric chamber reach the predetermined pressure, excess gas is vacated from the chamber through the relief valve.
In addition, regulations typically require two additional shutoff valves between the chamber and the oxygen supply, one of which is typically located inside the room proximal to the chamber, and the other of which is located just outside the room. Typically, these are manual ball valves that can be used to terminate the flow of oxygen from the supply.
Hyperbaric chambers are also required to be equipped with an emergency ventilation system that allows the operator to rapidly decompress the chamber. This system operates at pressures below the point of activation of the chamber overpressure relief valves. In some chamber designs, if the supply gas to the chamber is interrupted, function of the emergency ventilation mechanism may be compromised because the emergency ventilation system requires a gas supply to operate.
Although hyperbaric chambers as they exist today are relatively safe, there are instances where patients and others have been injured or killed as a result of the failures of the existing safety systems. For example, in one incident, a fire initiated by an ignition source introduced by the patient caused fatal burns to the patient. Because the oxygen supply was not cut off, and due to the ongoing fire, the pressure within the hyperbaric chamber increased to >120 psi. The chamber exploded, and parts of the chamber impacted the patient's wife at a high rate of speed, resulting in her death.